Composite decking cost calculator (per m², by state)
Composite and PVC deck boards in Australia cost from $63 to $426 per m² inc GST across 44 board sizes in 40 ranges, with a middle price of $143 per m² (prices checked up to 15 October 2026).
What the boards cost for your deck, at each board’s average price in your state.
Your deck and the result
Your deck
Board cost
Choose your state in “Your deck” to apply each board’s average price there to this deck. Prices include GST and are averaged within a state.
- Deck area priced
- 17.3m²
Cost per board
Choose a state above and every board priced there is listed here: what its boards cost for this deck at the board’s average price, how many sellers the average comes from, and how recent it is. Prices include GST; coverage is always stated and sample data is badged.
What the price leaves out: the frame underneath (a concept, not for construction)
| Item | Figure |
|---|---|
| Joists | 90 × 45 MGP10 H4 at 396 mm centres (Treated pine MGP10 (H3 / H4)) |
| Longest joist span | 1,170 mm |
| Bearers | 2 / 190 × 45 MGP10 H4 (double), 4 lines |
| Posts | 12 × 90 × 90 H4 post |
| Footings | 12 pads, 300–400 mm square |
| Clearance under the lowest member | 147 mm |
How this is worked out
A price per square metre is the price per lineal metre × 1,000 ÷ the board’s cover (its width plus the gap beside it, in mm). The board cost for your deck is that price × the deck’s area (17.3 m²), worked out for each board at its average price among the sellers in your state (the national average where no seller there prices it), with any seller more than 25% above or below the middle price left out.
The figures come from the same engine as the free deck designer, run on the server for a rectangular deck against the house. The span tables behind its framing have been checked by a structural engineer, but every framed figure is still a concept figure: concept plan, not for construction. Have a builder, building surveyor or certifier check any design before you build it.
Cutting and waste
Cut plan
| Material | Stock bought (m) | Cut (m) | Waste |
|---|---|---|---|
| Composite 137 × 23 — Charcoal | 140.4 | 124.8 | 11% |
| 90 × 45 MGP10 H4 — joists | 46.8 | 45.6 | 3% |
| 90 × 45 MGP10 H4 — rim joists | 9.6 | 9.6 | 0% |
| 2 / 190 × 45 MGP10 H4 (double) — bearers | 19.2 | 19.2 | 0% |
| 90 × 90 H4 post — posts | 2.4 | 1.8 | 27% |
The engine’s checks (3)
Checks
| Check | Detail |
|---|---|
| Extra rot protection near the ground | 19 frame pieces sit 400 mm or less above the ground. Wood this close to the ground gets extra rot protection (H4 treatment) instead of H3. Posts are always H4. Nothing for you to do. |
| Last row of boards ripped to 25 mm | The last row of boards has to be ripped (cut down lengthwise) to 25 mm wide — a full board is 137 mm. To finish on a full board, make the deck depth (out from the house) 31 mm smaller (3569 mm) or 112 mm larger (3712 mm). Strips narrower than about 69 mm are hard to fix down and can split or cup. |
| Council approval — VIC | In Victoria every deck attached to the house needs a building permit from a building surveyor, whatever its size. A planning permit from the council is usually not needed when the floor is 800 mm or less above the ground, unless a heritage or other overlay applies. Your deck is 17.3 m² and 450 mm high — confirm the requirements with your council before you build. |